1. Field of the Invention
The present invention relates to a flow meter, particularly for warm water heating systems.
2. Description of the Background Art
Flow meters of this type for flowing liquids are generally known. They are frequently used in warm water heating systems to register partial flows of a heating medium in various pipe lines, or branch lines, and to be able to monitor them during operation. Flow meters of this kind have an indicator scale, of which the respective position of an indicator rod, having a rebounding plate that is influenced by the flowing medium, can be read. Conventionally, the indicator scale is usually arranged on a surface of an inspection glass along a line.
In a conventional flow meter of this type, for example, as described in EP 0 884 514 B1, the indicator element as well as the measuring element are screwed opposite of each other with cylindrical attachments into a collector pipe, whereby a gap is formed between the lower end of the indicator element and the upper end of the measuring element. If such a flow meter is not used in the return flow, as taught in EP 0 884 514 B1, where the rebounding plate of the indicator rod is slidable in the internal bore of the measuring element and is exposed to direct flow, but is used in the forward flow, then it is necessary to influence the flow against the rebounding plate in order to avoid any turbulence of the flow against the rebounding plate. This is accomplished, for example, by arranging a pipe-shaped attachment in the area between the lower end of the indicator element and the upper end of the measuring element, which bridges this gap for the most part and is provided with openings, which influence the flow-through.
It was found in actual operation that in warm water heating systems, particularly after operation of the system was started or after the system was serviced, sharp-edged dirt particles are often transported with the heating medium. Since the annular gap between the outer perimeter of the rebounding plate and the internal bore of the measuring element is, for flow-technical reasons, very narrow, the danger exists that such dirt particles can get jammed or clogged in this annular gap, thereby blocking the function of the indicator.